{"id":"GHSA-6xvm-j4wr-6v98","summary":"Quinn affected by unauthenticated remote DoS via panic in QUIC transport parameter parsing","details":"### Summary\nA remote, unauthenticated attacker can trigger a denial of service in applications using vulnerable `quinn` versions by sending a crafted QUIC Initial packet containing malformed `quic_transport_parameters`. `In quinn-proto` parsing logic, attacker-controlled varints are decoded with `unwrap()`, so truncated encodings cause `Err(UnexpectedEnd)` and `panic`. This is reachable over the network with a single packet and no prior trust or authentication.\n\n### Details\nThe issue is panic-on-untrusted-input in QUIC transport parameter parsing.\nIn `quinn-proto` (observed in `quinn-proto 0.11.13`), parsing of some transport parameters uses a fallible varint decode followed by `unwrap()`. For malformed/truncated parameter values, decode returns `UnexpectedEnd`, and `unwrap()` panics.\n\n#### Observed output:\n```\nthread 'tokio-rt-worker' (2366474) panicked at quinn-proto/src/transport_parameters.rs:473:67:\ncalled `Result::unwrap()` on an `Err` value: UnexpectedEnd\n```\n\n### PoC\n#### Reproduces against the upstream Quinn server example.\n1. Start server:\n```\ncargo run --example server -- ./\n```\n2. Prepare PoC client environment:\n```\npython3 -m venv .venv\nsource .venv/bin/activate\npip install aioquic\n```\n3. Run PoC script [attack.py](https://github.com/user-attachments/files/25741713/attack.py) against server QUIC listener (default example target shown):\n```\npython attack.py\n```\n#### Observed output\n```\nthread 'tokio-rt-worker' (2366903) panicked at quinn-proto/src/transport_parameters.rs:473:67:\ncalled `Result::unwrap()` on an `Err` value: UnexpectedEnd\n```\n\n\n\n### Impact\nVulnerability type: Remote Denial of Service (panic/crash)\nAttack requirements:  Network reachability to UDP QUIC listener\nAuthentication/privileges: None\nWho is impacted: Any server/application using affected `quinn/quinn-proto` versions where this parse path is reachable; process-level impact depends on integration panic handling policy\n\n\nThis vulnerability was originally submitted by @revofusion to the Ethereum Foundation bug bounty program","aliases":["CVE-2026-31812","RUSTSEC-2026-0037"],"modified":"2026-09-10T03:50:37.796449419Z","published":"2026-03-11T00:09:19Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-03-11T00:09:19Z","nvd_published_at":"2026-03-10T22:16:18Z","cwe_ids":["CWE-248"],"severity":"HIGH"},"references":[{"type":"WEB","url":"https://github.com/quinn-rs/quinn/security/advisories/GHSA-6xvm-j4wr-6v98"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31812"},{"type":"WEB","url":"https://github.com/quinn-rs/quinn/pull/2559"},{"type":"PACKAGE","url":"https://github.com/quinn-rs/quinn"},{"type":"WEB","url":"https://rustsec.org/advisories/RUSTSEC-2026-0037.html"}],"affected":[{"package":{"name":"quinn-proto","ecosystem":"crates.io","purl":"pkg:cargo/quinn-proto"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.11.14"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-6xvm-j4wr-6v98/GHSA-6xvm-j4wr-6v98.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}